The galaxy sample used is a sub-sample of the ESO-Uppsala Catalog of Galaxies [1]} which was selected by eye
from photographic plates. It is only incomplete for very late Hubble types (T \(>6\) , i.e., later than Scd; [2]}). Values of \(V_{\rm flat}\) 
were determined from optical and radio observations. For the optical data, \(V_{\rm flat}\)  was
defined as half the difference between the maximum and minimum velocities of the H\(\alpha \)  rotation curves.
For the radio data, \(V_{\rm flat}\)  was defined as half the width of the HI profile between points where the intensity
falls to 50% of the highest values; these values were then corrected for dispersion and converted to optical rotation velocities
by multiplying by 1.03 and then subtracting 11 km s\(^{-1}\)  [3]}.
Disc half light radii, which are the result of \(I\) -band bulge-disc
decompositions from [2]}, are converted to disc scale lengths by dividing by 1.679 (the exact ratio of the half-mass
radius to the scale radius for a pure exponential disc).
Only those galaxies with rotation velocities greater than 125 km s\(^{-1}\)  are used. This helps us to avoid galaxies
with rotation curves which do not flatten out at the radii measured. The distribution of galaxies in \(j\) 
versus \(V_{\rm flat}\)  does not differ significantly from the galaxy sample commonly used in the literature [5]},
but it has a better completeness.
